Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1104 AM EST Sat Mar 09 2019 Valid 12Z Tue Mar 12 2019 - 12Z Sat Mar 16 2019 ...Heavy Snow/Wind Threat for the North-Central U.S. Wednesday and Thursday... ...Heavy Rain/Strong Thunderstorm Threat from the South-Central Plains/MS Valley to the Mid-South/Southeast Tuesday to Friday... ...Overview... It seems that the last in a series of potent storm systems in this active flow pattern will trek out of the Southwest/Four Corners region Tuesday and lift northeastward toward the Upper Midwest/Great Lakes by Thursday. This will spread a large area of potentially heavy rain/severe convection and runoff threat from the central/southern Plains through the Mid-South/Southeast as marginally cold air to the north supports a heavy snow/wind threat for the north-central Rockies/Plains and Upper Midwest. By next weekend, the pattern appears much quieter with high pressure forecast to dominate the western/central parts of the lower 48. ...Guidance and Uncertainty Assessment... Recent guidance has been inconsistent run to run with the timing of driving mid-upper level trough energy/height falls. However, guidance has been quite consistent showing ultimate development of yet another major storm to traverse the Southwest leading into powerful storm genesis over the central U.S. A concensus of latest guidance offers a solution in line with WPC continuity. ...Weather Highlights and Hazards... Main system of interest in the medium range will lift out of the Southwest and deepen quite smartly into southeastern Colorado by Wednesday morning. Precipitation will expand in coverage out of Arizona and New Mexico eastward, focused on the central/southern Plains (northern Texas northward) Tue/Wed. To the east, a front across the Gulf will lift northward as a warm front and bring widespread rainfall and embedded convection into the Mississippi/Tennessee Valley Wednesday then into Alabama/Georgia/southern Appalachians Thursday. The potential for several inches of rain exists over a large area that will be further refined over the next several days, but atmospheric and ensemble signals continue to be strong. To the north, cold enough air will support snow on the northwest/north side of the surface low that will occur with strong winds (i.e., possible blizzard conditions). A cold rain (perhaps over an inch to an inch and a half) will fall to the southeast of the surface low over some areas that will receive significant snow in the short term (e.g., southern Minnesota). The surface low will depart through southern Canada Friday as colder air is dragged in behind it across the Great Lakes, enhancing lake-effect snows. Temperatures will remain below average in the west but perhaps moderate just a bit by next weekend. In the east, post-front airmass Tuesday will be chilly (below average by a few degrees) but then warm up ahead of the central states' system by Thursday into Friday. Fracasso/Schichtel Additional 3-7 Day Hazards information can be found on the WPC medium range hazards chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, winter weather outlook probabilities and heat indices are at: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml